"Three years after the first 'once in a generation' financial crisis, we may now be entering the end game for a euro of 17 countries," said Graeme Leach, chief economist at the Institute of Directors, a London-based non-political organization comprising 43,000 business leaders worldwide, but primarily in the United Kingdom.

Incidentally, the U.K. was also the one country that staunchly opposed the latest deal, with Prime Minister David Cameron saying, "What is on offer isn't in Britain's interests."

Early Friday, European leaders, including 17 members of the eurozone, which share the embattled single currency, reached a deal for a new intergovernmental treaty to deepen the integration of national budgets.

With the exception of the U.K., it appears the plan also has the backing of the majority of the European Union.

But questions remain about the role of the European Central Bank. The ECB has been buying debt on a limited basis, as part of an emergency program, but there have been calls for more aggressive action.

Leach argues that the collapse of the euro is inevitable without the ECB's virtually limitless financial support.

ECB President Mario Draghi has firmly said, time and time again, that the central bank's only mandate is to prevent inflation.

"It's the ECB or bust," Leach said. "Unless the ECB begins to operate as a sovereign lender of last resort function, with massive purchases of eurozone public debt, the inexorable logic is that the eurozone will break up."

The latest moves are steps in the right direction, but much more is needed, say experts.

"All of the harebrained schemes invented so far to resolve the crisis in euroland remain half thought out, unfunded and unimplemented...and therefore, still harebrained," said Carl Weinberg, chief economist at High Frequency Economics.

European leaders, particularly from France and Germany -- the eurozone's two largest economies -- have had very different views on the ultimate role of the fiscal compact, and the latest proposals are just "too little, too late, and miss the structural problem," said Leach.

Germany has been strongly opposed to sending the ECB down a path of printing money to stabilize Europe's economy.

"Printing money is associated with hyperinflation, the collapse of the Weimer Republic, and the rise of Hitler," noted Leach. "From a German perspective the question is that, once the ECB has lost its virginity printing money, just how promiscuous could it become."

And even if a "catastrophic event" changes Germany's mind, Leach says hurdles remain because "the ECB's balance sheet is already shot to pieces. It's massively over-leveraged."

Though investors and experts alike expect the ECB to intervene for fear of the alternative, Leach doesn't think that a fundamental change is likely.

And with no other surefire way out, Europe's hard hit "Club Med" economies like Greece, Italy and Spain could be driven "to the point where they deem it in their national interest to exit the euro," despite the immediate economic, political and practical consequences. And it could happen in the next six months, he said.

Not everyone agrees.

Evolution Securities analyst Elisabeth Afseth only sees a 10% chance of a euro break-up happening that soon, but agrees that European leaders have a lot of work to do, and kicking the can down the road only increases the risks of an end to the eurozone.

"In the short-run, it's beneficial for everyone to stay in the eurozone because the cost and pain of a break-up would be huge," she said. "But European leaders have to be careful in how they formulate the fiscal union. If the terms are all wrong, that's not good for the long run, and the danger of a break-up will remain."

Afseth said the fiscal union needs to focus more on boosting economic growth, rather than just pushing for budgetary discipline and fiscal austerity. And it needs to advocate for pooling the eurozone's debt together, so the region can issue eurobonds, another highly contentious topic among Europe's political leaders.

Despite the multitude and extent of the political disagreements that could lead to the eurozone's crumble in the near-term, more optimistic experts say Europe's leaders will likely find a middle ground to avoid the severe economic consequences.

"The political arguments are strong, but they come against a hard economic reality," said Andrew Milligan, head of global strategy at Standard Life Investments in Edinburgh, Scotland, noting that the costs for a single country leaving the eurozone could amount to at least 15% or 25% of its economy, if not more.

"A break-up could result in very major recession in Europe, and so it's hard to imagine how any politicians and governments could possibly make a conscious, voluntary decisions to leave the eurozone," said Milligan.

But that doesn't mean it won't ever happen.

Milligan said leaders will likely lurch from crisis to crisis, and Europe's leaders will keep having to face complex political hurdles.

"The chances that the eurozone will remain intact over the next several months are high, but the danger could get worse over the next couple of years, as they try and transition toward any sort of fiscal union," said Milligan.